Although Apple has done a better job of moving its Mac users along with each new operating system than has rival Microsoft, the Cupertino, Calif. company has been unable to eradicate fragmentation as it accelerated upgrades to an annual cadence.
According to data from analytics firm Net Applications, three OS X editions that were three years or older retained five or more percentage points of user share last month. Those three editions -- 2009's Snow Leopard, 2011's Lion and 2012's Mountain Lion -- powered 20% of all Macs in April. When 2007's Leopard was included, the number climbed to 21.3%.
There's no question that Apple's policy of giving away its OS X upgrades -- a practice begun in 2013 with Mavericks -- has reduced fragmentation by pulling Mac owners onto the newest edition faster than did versions that carried a price tag. The current OS X Yosemite, for example, accounted for 57.5% of all Macs in April, 23 percentage points higher than where Mountain Lion stood at the same point in its post-launch timeline. Mountain Lion was the last upgrade that cost customers money.
But the annual upgrades, even free, have been unable to eliminate laggards. While Yosemite powered the majority of Macs last month, Mavericks accounted for 21%, Mountain Lion and Lion for 6% each, Snow Leopard for 8%, and Leopard for nearly 2%. More than four in every 10 Macs ran an aged OS in April.
And older OS X editions dwindle in importance at a very slow rate: Over the past six months, Snow Leopard, Lion and Mountain Lion -- the upgrades launched between 2009 and 2012 -- have averaged a decline of less than half a percentage point each month.
By the time Apple issues its next edition of OS X -- like its two predecessors, probably tagged with a California location name -- 25%, or a quarter of all Macs, will still be running Mavericks or earlier.
Those numbers stand in stark contrast to iOS, Apple's mobile operating system. By Apple's tally, 82% of all iOS devices now run version 8, which was released a few weeks before Yosemite last fall. 2013's iOS 7 powered only 17% of all devices, while the rest of the even-older iOSes accounted for just a measly 2%.
Operating system makers like Apple and Microsoft may talk up accelerated release tempos, and analysts may see similarities between those efforts on personal computers and the long-standing upgrade practices by smartphone owners, but the truth is that there's no evidence to show consumers take to a new computer OS at the same pace as they do mobile operating systems.
Eliminating fragmentation is a goal of all OS makers, for it homogenizes the user base, providing developers a large and theoretically lucrative target for apps and services that leverage the latest features and APIs (application programming interfaces). More customers on the latest version can also reduce support costs, and newer OSes are typically more secure.
Microsoft, especially, has been talking up fragmentation, or the reduction of fragmentation, among its Windows users as it beats the Windows 10 drum.
"Today Windows customers are spread across many versions. This fragmentation makes it challenging for developers to delight our customers with applications," said Terry Myerson, the Microsoft executive who leads the Windows group, in January when he announced that Windows 10 would be a free upgrade for consumers and some businesses.
In fact, Microsoft has set an ambitious goal of getting Windows 10 onto 1 billion devices -- or two-thirds of those currently running Windows -- by mid-2018, part of its anti-fragmentation strategy as it pivots toward making money from services and apps.
Windows is much more fragmented than is OS X, of course: As of April, about 17% of all Windows PCs ran 2001's Windows XP, more than the share of Windows 8/8.1, Microsoft's newest OS. And unlike Apple's most popular edition, Microsoft's was 2009's Windows 7, which accounted for 64% of all in-use Windows versions.
Operating systems on personal computers have a long "tail," something even Apple has found out.